Bipolar transistors, in discrete form and within integrated circuits, are minority carrier devices. Although many parts of these integrated circuits can operate down to −80 or −100 degrees Celsius, at more extreme cold temperatures, the current gain of the bipolar transistors drops to levels that make the integrated circuits functionally unusable.
Majority carrier devices, such as insulated gate MOSFETs and MESFETs as well as junction FETs (JFETs), however, do not have this limitation to such an extent. In fact, the channel resistance of these devices reduces at extreme cold temperature, which can improve performance. Both insulated gate and junction FETs are available as discrete elements or combined into an integrated circuit.
When exposed to ionizing radiation, the gate threshold of insulating gate devices, including CMOS parts, can shift considerably due to accumulation of radiation deposited charge within the gate oxide. Unless special methods are used to compensate for this voltage shift, most commercially available insulating gate devices are not functional after high radiation exposure.